1 Technical Field of the Invention
The present invention relates generally to a hydrogen sensor measuring the concentration of hydrogen contained in gasses, an overcharge/overdischarge detector and a hydrogen leakage detecting apparatus using a hydrogen sensor.
2 Background Art
Charge/discharge control systems are known which are designed to avoid overcharging and overdischarging of a storage battery mounted in electric vehicles or hybrid vehicles. Usually, the overcharging or overdischarging of a battery will cause combustible hydrogen to be generated within a battery chamber. It is, thus, necessary to inhibit the overcharging and overdischarging of the battery for safety purposes. The systems are designed based on the fact that a battery temperature rises during the overcharging and have temperature sensors measuring such a temperature rise of the battery. The overdischarging is detected based on the fact that the overdischarging will cause the voltage of the battery to be decreased.
It is also necessary for fuel cells using hydrogen to stop an operation of a hydrogen feed system feeding the hydrogen to a fuel electrode of the fuel cells if leakage of hydrogen occurs.
However, the above systems require installation of temperature sensors one for each cell of the battery. An increase in battery will, thus, result in a great increase in temperature sensor. During overdischarging, the temperature of the battery does not rise. The temperature sensors are used only in detecting the overcharging. Other means is, thus, needed for detecting the overcharging, thereby resulting in complex of the system.
The fuel cells are desired to detect the hydrogen leakage using a high sensitive yet simple structure.